Signal distributing and synchronizing system



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xR 2,685,681 1 954 F. E. TIDBALL 2,685,681

SIGNAL DISTRIBUTING AND SYNCHRONIZING SYSTEM 7 Filed June 3, 1952 2 Sheets-Sheet l SCOPE VERTICAL AMP.

Aug. 3, 1954 F. E. TIDBALL 2,685,681

SIGNAL DISTRIBUTING AND SYNCHRONIZING SYSTEM Filed June 5, 1952 2 Sheets-$heet 2 FIG. 2. M

59 KEYING TOOTH INVENTOR FRANK E. TIDBALL zw w'ef ATTORNEY Patented Aug. 3, 1954 UNITE STATES SIGNAL DISTRIBUTING AND SYNCHRONIZ- ING SYSTEM Frank E. Tidball, Minneapolis, Minn, assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Application June 3, 1952, Serial No. 291,408 i 4 Claims. 1

This invention relates in general to multiplex electrical signalling devices and in particular to mechanical synchronizing devices for directing time displaced signals intoa plurality of analyzing channels in dependency on the time occurrence thereof in successive time periods and for providing keying signals indicative of the start of each time period.

Wholly electronic devices suitable for perform ing the above operations and employing trigger circuits and gating tubes can be designed with little difficulty. Such electronic devices can be made quite reliable and trouble-free and are in reality the only practical type of apparatus suitable for high speed switching operations. In spite of this situation there are numerous instances where low speed switching rates permit the use of mechanical sequencing devices or commutators, particularly where it is desired to keep circuit complexity to an absolute minimum or to operate under conditions of severe mechanical vibration likely to have adverse effect upon the useful life ofdelicate electron tubes.

One of the chief drawbacks in the use of a mechanical commutator device for multi-purpose operation is in the accuracy required in the manufacture and assembly of the component parts so that synchronism is maintained in the switching provided by the several commutators. Such accuracy requirements mean higher manufacturing costs resulting in a higher initial cost. Additionally maintenance costs are also higher because in many instances complex equipment and highly skilled personnel are required for adjustments after even comparatively simple servicing operations such as replacing brushes which have been removed for cleaning or renewing.

Accordingly it is an object of the present invention to provide a simple and sturdy mechanical sequencing device for channeling multiplex signals into a plurality of analysing channels.

Other and further objects and features of the present invention will become apparent upon a careful consideration of the following description and the accompanying drawings wherein:

Fig. 1 shows a block diagram of a type of system wherein the apparatus of the present invention may be utilized; and

Fig. 2 is a schematic diagram of a combined synchronizing and channeling apparatus embodying the invention.

With particular reference now to Fig. l of the drawing, a specific combination of apparatus employing the principles of the present invention is shown. In this apparatus, it is desired to distribute incoming pulse signals, as obtained from the pulse signal source ID, to a plurality of indicator devices, as represented by the oscilloscopes ll, l2, l3, and 14, which may be referred to include cathode ray tubes of a conventional type having two perpendicularly disposed beam deflection means together with intensity control means. The scopes l l-l l receive the distributed signals from the pulse signal source I!) through the synchronizer and distributor it which device is shown in detail in Fig. 2 and later described herein. The distributed signals are applied as vertical deflection signals through the amplifiers l1, l8, l9 and 2G to the scopes H-l l respectively. Alternately, the signals could be applied to the scopes H-M as intensity modulation signals.

Horizontal deflection or sweep time base signals for the scopes are obtained from the horizontal sweep circuit l6 which is connected to the synchronizer and distributor I5. As shown in Fig. 1 all scopes receive the same horizontal deflection signals, however only one scope gives indication at any one instant and that is the one which is receiving the distributed output from the synchronizer and distributor l5. The horizontal sweep circuit may be of a triggered or slave type operative in response to a pulse type signal produced by the synchronizer portion of the device of block i5. Thus, in the apparatus of Fig. 1, the horizontal sweep block it will in-- clude an output amplifier of a type suitable for the type of deflection employed whether it be electro-static or electromagnetic.

The specific circuit shown in Fig. 2 illustrates in schematic form a preferred embodiment of the features of the present invention. This device of Fig. 2 is an apparatus which would be suitable to provide the combined operations of synchronizing and distributing as required for the equipment located in block l5 of Fig. 1.

The apparatus of Fig. 2 is built around a me chanical device 2 l, shown schematically as a single multi-segment commutator having segments 22, 23, 2d, 25, etc., a slip ring 2%, brush assembly 2'1, and a brush mounting and motive means 28 such as a mounting arm suitably journalled and rotated by a motor not shown. The brush contacting the segments 22, 23, 24, 25, etc. is of sufficient width to bridge the insulating gap between adjacent segments so that in motion thereof, it momentarily contacts two segments as it travels from one segment to another. In the showing of Fig. 2, a twelve segment commutator has been represented with typical output circuits connected to four of the segments. It is to be understood that in actual apparatus there would ordinarily be as many electronic output circuits as there are commutator segments.

Each electronic output circuit. for example that connected to segment 22, includes a soft tetrode electron tube 29 having its grid 39 connected to commutator segment 22 and to a source of negative potential, typically of minus l5 volts, through a resistance 3|. The cathode 32 and grid 33 are connected to ground while the anode 34 is connected to a source of B-plus potential through resistance 35. Obviously triodes or other multielectrode tubes can be used in place of tube 29. Additionally the anode S4 is by-passed to ground by capacitance 36 and coupled to an output terminal 3? by means of a short time constant circuit comprising capacitance 38 and resistance 39. Normally, therefore, the potential at the grid 39 is such that tube 29 is held non-conductive by virtue of the hevay bias voltage applied to its grid. Thus in the non-conductive condition, capacitance 36 becomes charged to the B-plus potential through resistance 35.

The slip ring 26 of the mechanical device is connected to the cathode ii of a triode electron tube 4!, to the cathode Q2 of a diode electron tube 43 and to ground through a resistance 44. The tube 4| has its anode 35 connected to a source of B-plus potential typically of 150 volts and its grid at connected to a source of input signals to be separated on the basis of time occurrence as obtained at the input terminal 4?. Additionally grid 15 is connected to a source of biasing potential typically of minus 75 volts through a grid return resistance 48.

Tube 43, the cathode 42 of which has previously been mentioned as being connected to slip ring 26, has its anode 39 connected to the grid 55 of a pentode type electron tube 51. Addition-- ally anode 49 is connected through signal ideveloping resistance 52 to a tap point of a voltage divider comprising resistances 53 and 54 connected between a source of biasing potential typically of minus 75 volts and ground. Typically the potential of the tap point between resistances 53 and 54 is minus 25 volts. Additionally the cathode 55 of tube 51 is also connected to this tap point on the voltage divider. By virtue of this connection, tube 5! is thus provided with zero bias when tube 43 is non-conductive, the grid 58 and cathode 55 being at the same potential. The screen grid 55 of tube 5! is connected with a suitable source of potential typically of 150 volts positive with respect to ground, whereas the anode 57 is connected to a source of B-plus potential typically of 300 volts positive with respect to ground through the signal developing anode resistor 58. Additionally the anode 5! is connected to a keying pulse output terminal 59 by means of coupling circuit including capacitance E and resistance In the operation of the apparatus of Fig. 2, sequential input signals of pulse type and of positive polarity are supplied to terminal 41. These signals may be of many forms, but the general problem is that of dividing them into separate output lines on a basis of time occurrence so that they appear as pulses at the individual output terminals 37, 62, 63, G5, etc., separated on the basis of their time occurrence. The mechanical apparatus 2! is operated typically by means of a suitable motor drive producing rotation of the brush assembly 2'! in a clockwise direction at a desired speed. The brush assembly 2'! being, for example, a pair of brushes providing contact between individual segments of the commutator and the slip ring 25 and being insulated from ground so as to produce the sequential connection of the individual segments of the commutator to the slip ring 26. With this arrangement the brushes make connections which form a series voltage divider path from ground through resistance 44, slip ring 216 and one of the segments, 22 for example, and its corresponding resistance, 3| for example, to the minus '75 volt potential. This voltage divider action may typically place a potential at the cathodes 40 and c2 of minus 20 volts when the brush assembly 21 contacts the associated single segment such as 22. In this situation, with the cathode of tube 43 at minus 20 volts and the anode 49 thereof at a potential of minus 25 volts, tube 43 is non-conductive so that no potential is developed across resistance 52 and tube 5| is provided with substantially zero bias so that it is heavily conductive with the anode 51 thereof at a low potential. The brush assembly 2'! which contacts the segments of the commutator, as has been previously mentioned, is of sufficient width to bridge the insulating gapbetween adjacent segments. Thus with this situation, whenever the brush assembly bridges the gap between two adjacent commutator segments, such as segments 22 and 23 for example, the slip ring 26 and cathodes 40 and 42 are actually connected to the minus 75 volt potential through two resistances of equal magnitude, resistances 3| and 62. Voltage divider action between the parallel connected resistances 3i and B2 in series with the single resistance 34 will then lower the potential of the cathodes 40 and 42 to a typical potential of approximately 32 volts. In this condition then tube 43 will become conductive to produce a potential drop across resistance 52 of approximately 7 volts. i This grid bias change effects a substantial reduction in the conductivity of tube 5| to produce in increase in potential at the anode 51. This potential increase, however, will persist for only a very short period of time during which the brush assembly 27 bridges the gap across two adjacent commutator segments. It is to be noted, of course, that the diode 43 prevents the application of signal pulses as applied to terminal 47 to the grid 50 of tube 5|. The only possibility of any interference is when an input signal pulse is applied to terminal 4'! at a precise moment at which the brush assembly 2'! bridges the gap between adjacent commutators. The low impedance cathode follower action of tube 4| will almost completely mask any conductivity changes at the cathodes 40 and 42 due to bridging action of commutator segments. Due to this situation, which may prevail occasionally, it is therefore desirable that any so attached generator fed from the terminal 59 be of the fly-wheel type, such as is employed in current television receivers and which is merely synchronized by the pulse obtained from terminal 59 rather than being directly triggered thereby.

The circuit thus far described provides output synchronizing impulses at the terminal 59 in coincidence with each instant of time at which the brush assembly 21 contacts one of the segments 22, 23, etc., to start the time instant allotted to signal representation from each.

The input signals of positive polarity delivered to terminal 4'! are divided on a time occurrence basis to produce ionization of appropriate gas tubes 29, etc., to provide output signals in corresponding output lines 3?, '62, B3, 64, etc. Output signals occur in coincidence with initiating input signals.

Mechanical complexity is reduced because only a single multi-segment commutator is required to provide the divided output signals in the separate output chambers and the synchronizing signals in a separate line for indicating the start of a time period for one of the output channels.

kl. l

Typical values for various circuit elements in the drawings are as follows:

From the foregoing it is obvious that many modifications in the features of the present invention may be made without exceeding the scope thereof as defined in the appended claims.

What is claimed is:

1. A signal distributing system for directing applied si nals into a plurality of output channels on a basis of their time occurrence and also providing synchronizing signals in coincidence with the transition from one output channel to another comprising, a multi-segment commutator having at least as many insulated segments as output channels in the system, each segment being connected to an 'output channel, brush means suitably mounted and driven for sequentially contacting the segments said multi-segment commutator, said brush means having sufilcient contacting length measured in its path of travel to span the insulating space between adjacent segments, a source of control potential, a plurality of control resistors individually connected between each commutator segment and the source of control potential, signal input means connected to said brush means for delivering input signals to said brush means, and control means connected to said brush means for providing an output synchronizing signal upon contact of the brush means with adjacent segments.

2. A signal distributing system for directing applied signals into a plurality of output channels on a basis or their time occurrence and also providing synchronizin signals in coincidence with the transition from one output channel to another comprising, a multi-segment commutator having at least as many insulated segments as output channels in the system, brush means suitably mounted and driven for sequentially contacting the segments of said multi-segment commutator, said brush means having sufiicient contacting length measured in its path of travel to span the insulating space between adjacent segments, a plurality of electron tubes having anode, cathode, and control grid electrodes, means independently connecting a grid of each of said electron tubes to an individual commutator segment, a source of biasing potential exceeding the cut-01f voltage of the electron tubes, a grid resistor for each electron tube connected between the tube grid and the source of biasing potential, signal input means connected to said brush means for deliverin input signals to said brush means, and control means connected to said brush means for providing an output synchronizing signal upon contact of the brush means with adjacent commutator segments.

3. A signal distributing system for directing applied signals into a plurality of output channels on a basis of their time occurrence and also providing synchronizing signals in coincidence with the transition from one output channel to another comprising, a multi-segment commutator having at least as many insulated segments as output channels in the system, brush means suitably mounted and driven for sequentially contacting the segments of said multi-segment commutator, said brush means havingsufficient contacting length measured in its path of travel to span the insulating space between adjacent segments, a plurality of gas-filled electron tubes having anode, cathode, and control grid electrodes, means independently connecting a grid of each of said electron tubes to an individual commutator segment, a source of biasing potential exceeding the cut-off voltage of the electron tube, a grid resistor for each electron tube connected between the tube grid and the source of biasing potential, anode current control means for said electron tubes for interrupting anode current flow therein,

with the transition from one' output channel to another comprising, a multi-segment commutator having at least as many insulated segments as output channels in the system, brush means suitably mounted and driven for sequentially contacting the segments of said multi-segment commutator, said brush means having sufficient contacting length measured in its path of travel to span the insulating space between adjacent segments, a plurality of gas-filled electron tubes having anode, cathode and control grid electrodes, means independently connecting a grid of each of said electron tubes to an individual commutator segment, a source of biasing potential exceeding the cut-off voltage of the electron tubes, a grid resistor for each electron tube connected between the tube grid and the source of biasing potential, anode current control means for said electron tubes for interrupting anode current flow therein, signal input means connected to said brush means for delivering input signals to said brush means, control means connected to said brush means for providing an output synchronizing signal upon contact of the brush means with adjacent commutator segments, a unilateral signal path connected to said brush means including a unilateral conductive element and a biasing source therefor, said signal path operative to conduct only when the brush potential falls to a low value upon contact with adjacent commutator segments, and amplifier means connected to said unilateral signal path and responsive to conduction therein to deliver an output synchronizing signal.

References Cited in the file of this patent UNITED STATES PATENTS Graham Jan. 1, 1952 

